Method of electrically welding



' A. SCHMIDT. METHOD OF ELEETRICALLY WELDING.

APPLICATION FILED JULY 26,19!!!- 1,340,412.

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Patented May 18, 1920.

UNITED STATES PATENT OFFICE.

ALBERT SCHMIDT, OI! FLINT, MICHIGAN, ASSIGNOR TO CHAMPION IGNITIONCOMPANY, 01 FLINT, MICHIGAN, A CORPORATION OF MICHIGAN.

METHOD OI ELEOTRICALLY WELDING.

Specification of Letters Patent. Patented May 18, 1920.

Application filed July 26, 1918. Serial No. 248,808.

at Flint, in the county of Genesee and State of Michigan, have inventedcertain new and useful Improvements in Methods of Elec,

trically Welding, of which the following is a specification, referencebeing had therein to the accompanying drawings.

vThe invention relates to the art of electrical welding and it is theobject of the in vention to facilitate the welding togetherof elementsreatly varying in mass. Speclfically it 1s an object to electricallyweld electrodes to spark plug casings, but the invention is clearlyapplicable to many other uses. In the present state of the artelectrical welding is' easily effected between members which areapproximately of the same size adjacent to the weld, but where oneelement is of much greater mass than .the other, difficulty isencountered. This is due to the fact that the smaller element will beoverheated and possibly fused before the metal in the abutting elementof larger mass is raised to the welding temperature. The

overheating of the smaller element is partly due to its greaterelectrical resistance and consequent greater generation of heat, but

chiefly it is due to the relatively slow dissipation of heat therefrom.On the other hand, the heat generated in or conducted to eater mass isvery rapidly ment at the abutting point. I have also I devised a methodby which successive welds may be rapidly performed and without" therequirement 0 a high degree of skill on the part of the workman.

In the drawings: Figure 1 is an elevation of a spark plug casing with anelectrode welded thereto by improved method; ig. 2 is a sectionalelevation illustrating the method of the welding;

Fig. 3 is a cross-section on the line 33' of 2 showing the clamping jawsengaged with the work but before the application of pressure;

Fig. 4 is a similar view when the jaws are pressed together;

Fig. 5 is an enlarged view of a portion of Fig. 2 showing the manner ofpressing two members to be welded in contact with. each other.

In the'manufacture of spark plugs it is usual to form a groundedelectrode of wire formed of high fusing material such as nickel ornickel alloy. This electrode is usuall attached to the spark plug casingby drilling a hole in the annular wall of the casing and inserting theend of the 'wire thereinto. This operation is difficult and expensive,due to the time and skill required and also to the fact that the 'drillsare frequently broken Furthermore, the electrode when inserted' in thehole in the casing, is not in molecular contact with the has heretoforebeen thought impracticable by reason of the small diameter of the wireand the comparatively large mass of the metal casing. Attempts todissipate the heat from the wire have heretofore been unsuccessful dueto the small amount of surface exposure and the difiiculty of formingheat conducting contacts therewith. Even' where the wire is-clamped inmaterial of the highest thermal conductivit such, for instance, assilver, there is still difficult in dissipating the heat with suflicientrapid ity to ualizethe temperature of the electrode with that of thecasing at the point of contact. I have discovered that'by applying highpressure to the work from a contactin surface of greater hardness, thetherma conductivity is greatlincreased even where the materials use havenot a hi h coefficient of conductivity. I have furt er discovered thatby app ying high initial pressure to the contacting memmass.

bers to be Welded the temperature i n the element of smaller mass willbe reduced by thermal conduction to the element of greater As aconsequence of these discoveries, I am able to successfully weld anelectrode to a spark plug casing and perform similar operations uponother elements varying in mass.

As shown in Fig. 1, A is the body of the spark plu casing of anysuitable construction, and T is the electrode to be welded thereto. Thiselectrode is preferably cut from a continuous wire C, which may be fedto the welder by suitable means such as the feed rolls D, and cutofi' bya shear E. F and F are clamping jaws for en gaging and holding theelectrode during the welding operation and which form electrode andthermal contact therewith. These jaws are preferably formed of hardermaterial than that used for the electrode or other work, and wherenickel or nickel alloy is used for the electrode I preferably employtungsten for forming the jaws. As shown, G and G are tungsten inserts inthe body of the jaws, these inserts bein formed with ooves H and H forem racing the elec+ trode. As shown in Figs. 3 and 4 the clamping of thework by the jaws produces a deformation of the surface of the softermaterial so as to conform the same exactly to the shearblade E bein theharder surface and to produce in efiect molecular contact therewith.Furthermore, the pressure applied is sufficient to squeeze out anyintervening film of material which might interfere with theconductivity. The jaws are preferably extended the entire length of theelectrode from the point where it is sheared from the wire C to near theopposite end. There is, however, a pro? jecting portion of sufiicientlen 11 to avoid any s ort circuitin between t e jaws and f h d rovige ort e necessary u tting inci enta to t e forming of the wel c l Inoperation, .the wire C is first fed through the se arated jaws F and Fand is then. clampeg. by pressure of said jaws,

preferably not complete y severing t e wire at the start. The casing Ais then moved into contact with the projecting end of the electrode andwith suflicient pressure to form a slight deformation of the contactingsurfaces assuring good conductivity therebetween. The electrical currentfrom -a transformer, or other source of supply as indicated at -J, isthen turned on and continued until themetal at the point of contact israised to the welding temperature. Duri this interval heat is ra idlyconducte from the electrode into t e jaws F and F and also into thecasingA. Consequently, the tem rature will rise uniformlyon each side 0the joint and in predealso engaged but termined time interval the ,weldwill be effected. The currentis then cut out and the continuingdissipation of heat will quickly set the weld. The shear E is thenactuated to completely sever'the electrode from the wire C after whichthe jaws are separated and the electrode removed.

My improved method is one particularly adapted for .use inautomaticwelding machines inasmuch as the variables are largelyeliminated and the successive operations may therefore be performed bytimed mechanism.

What I claim'as my invention is:

1. In the method of electrically welding,

the step of applying. pressure to the work by a contacting bodysuflicient to produce a deformation in the surfaces of the workcontacting with the pressure applying "body.

2. In the method of electrically welding,

a contacting body of larger mass and greater surface hardness suflicientto produce uniform thermal conductivity in successive operations.

5. The method of electrically welding,

comprising the intermittent feeding of stoc for the smaller element,clamping the projecting portion of said stock with suffi.-

clent pressure to produce uniform, thermal conductlvlty in successiveoperations, contacting and applying pressure between the clamped stockand the cooperating element to be welded thereto, passing an electricalcurrent through the elements to effect the heating and welding thereof,and severing the clam d rtion' fromthe remainder of 116 the stock anreleasin the clamp.

6. In-the method 0 electrically welding elements of different mass, thestep of applyin tending to balance said varying capabilities.

8. The method of electrically welding,

comprising. the pinching of one element by a shearing member, forcingsaid element. into contact with the second element and coincidentallypassing an electric current ajualize the heat dissipa- 95 means tosubstantially equalize the heat 'ssipation from the smaller and larger120 therethrough for a predetermined period of time, and finallyfinishing the shearing of said first element.

9. The method of electrically welding, comprising the inching of oneelement by a shearing mem' r, forcin said element into contact with thesecon element, coincidentally passing an electric current therethroughfor a predetermined period of time,

finishing the shearing of said first element, and retaining saidelements in position after the cutting out of the current untilsuflicient heat is dissipated from the oint of contact between saidelements to solidify the metal.

' In testimony whereof I afiix my signature.

ALBERT SCHMIDT.

